The goal of the proposed Phase I work is the development of a painless, mininimumly invasive method of blood sampling and assay that will especially benefit pediatric and neonatal patients by eliminating the problems of pain and sample volume associated with current phlebotomy techniques. This new technology employs a disposable microsampling and assay device made using silicon microfabrication techniques common in the electronics industry. This single-use microdevice has a silicon microneedle comparable in size to a human hair that can puncture the skin painlessly and withdraw a sub-microliter volume of blood into an integrated microchannel/cuvette. The Phase I work will focus on the design and fabrication of microsampling devices, possibly containing multiple optical microcuvettes in a single device, and the development of a complete engineering prototype instrument. Direct optical assays for total hemoglobin and hematicrit will be developed and demonstrated. These two independent measurements allow for the accurate determination of mean corpuscular hemoglobin concentration, an indicator of anemia. Total hemoglobin and hematocrit are commonly used as markers for many conditions, including: anemia and polycythemia, dehydration, excessive bleeding, cirrhosis, and certin cancers and other chronic illnesses. Successful completion of this work will lead to the development of a novel blood testing system for independent measurement of total hemoglobin and hematocrit in sub-microliter blood samples. This instrument will be of particular benefit to pediatric and neonatal patients because of its lack of pain and small sample volumes. Its ease of use will also make it attractive for nursing homes, home health care, and other out-patient point-of-care applications. [unreadable] [unreadable] [unreadable]